Results 221 to 230 of about 791,112 (289)

<i>N</i> =1 Super Virasoro Tensor Categories. [PDF]

open access: yesCommun Math Phys
Creutzig T   +3 more
europepmc   +1 more source

On Sparsity Conditions Guaranteeing a Fractional Coloring

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT A graph has an ( a : b ) $(a:b)$ ‐coloring if there exists an assignment from the vertices to subsets of { 1 , … , a } $\{1,\ldots ,a\}$ with size b $b$ such that adjacent vertices are assigned disjoint subsets. Odd girth at least 2 k + 1 $2k+1$ is a necessary condition for a graph to have a ( 2 k + 1 : k ) $(2k+1:k)$‐coloring.
Ilkyoo Choi
wiley   +1 more source

A Note on Extendable Sets of Colorings and Rooted Minors

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT DeVos and Seymour proved that for every set C $C$ of 3‐colorings of a set X $X$ of vertices, there exists a plane graph G $G$ with vertices of X $X$ incident with the outer face such that a 3‐coloring of X $X$ extends to a 3‐coloring of G $G$ if and only if it belongs to C $C$.
Zdeněk Dvořák, Jan M. Swart
wiley   +1 more source

Equivalent Formulation of Thomassen's Conjecture Using Tutte Paths in Claw‐Free Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT We continue studying Thomassen's conjecture (every 4‐connected line graph has a Hamilton cycle) in the direction of a recently shown equivalence with Jackson's conjecture (every 2‐connected claw‐free graph has a Tutte cycle), and we extend the equivalent formulation as follows: In every connected claw‐free graph, any two vertices are connected
Adam Kabela   +2 more
wiley   +1 more source

Obstructions for Homomorphisms to Odd Cycles in Series‐Parallel Graphs

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT For a graph H $H$, an H $H$‐colouring of a graph G $G$ is a vertex mapping ϕ : V ( G ) → V ( H ) $\phi :V(G)\to V(H)$ such that adjacent vertices are mapped to adjacent vertices. A graph G $G$ is C 2 k + 1 ${C}_{2k+1}$‐critical if G $G$ has no C 2 k + 1 ${C}_{2k+1}$‐colouring but every proper subgraph of G $G$ has a C 2 k + 1 ${C}_{2k+1 ...
Eun‐Kyung Cho   +3 more
wiley   +1 more source

Characterization of Graphs Without Even F $F$‐Orientations

open access: yesJournal of Graph Theory, EarlyView.
ABSTRACT A graph G $G$ is 1‐extendable if every edge belongs to at least one 1‐factor of G $G$. Let G $G$ be a graph with a 1‐factor F $F$. Then an even (odd) F $F$ ‐orientation of G $G$ is an orientation in which each F $F$‐alternating cycle has exactly an even (odd) number of edges directed in the same fixed direction around the cycle.
Marién Abreu   +3 more
wiley   +1 more source

Home - About - Disclaimer - Privacy